Black Obsidian
Obsidian (Volcanic Glass)
igneous
Category
Organic Mineraloid And Mineral
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Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70–75% SiO2)
igneous
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
igneous
Amber
Succinicum (Organic compound, primarily C10H16O)
Organic Gemstone (Mineraloid)
Probable amber fragment
Amber (fossilized plant resin; chiefly amorphous organic resin, commonly dominated by succinite)
gemstone
Precious Opal
Hydrated Silica (SiO2·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
igneous
Boulder Opal
Hydrated Silica (SiO2·nH2O)
mineraloid
Cobalt Glass Slug (Man-made Glass)
Amorphous Silica with Cobalt Oxide (SiO2 + CoO)
mineraloid
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Obsidian
Volcanic glass
igneous
Obsidian
Volcanic Glass (felsic composition)
igneous
Obsidian
Volcanic Glass (Silicon Dioxide with impurities)
igneous
Common Opal with Host Rock
Opal (Hydrated silica, SiO2·nH2O)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Limonite (Ironstone) Concretion
FeO(OH)·nH2O (Hydrous ferric oxide)
sedimentary
Limonite (Yellow Ochre)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
mineral
Precious Opal
SiO2·nH2O (Hydrated Silicon Dioxide)
mineraloid
White Precious Opal
Hydrated Silica (SiO2·nH2O)
mineral
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
mineral
Mahogany Obsidian
Volcanic glass (Silicon Dioxide with Hematite/Magnetite inclusions)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
igneous
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
mineraloid
Bumblebee Jasper
Anhydrite-Aragonite mixture with Orpiment and Realgar
mineraloid
Black Opal (Triplet)
Hydrated Silica (SiO2·nH2O)
mineral
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
igneous
Snowflake Obsidian
Volcanic glass containing Spherulitic Cristobalite (SiO2)
igneous
Common Opal (Potch)
Hydrated Silica (SiO2·nH2O)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
igneous
White Opal (Common)
Hydrated Silica (SiO2·nH2O)
mineral
Cullet Glass (Man-made Glass Slag)
Amorphous Silica (SiO2) with chemical additives
Mineraloid
Mahogany Obsidian
Obsidian (SiO2 + Fe2O3)
igneous
Opal (Precious Opal)
Hydrated Silica (SiO2·nH2O)
mineral
Snowflake Obsidian
Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)
igneous
Obsidian
Volcanic glass (silica-rich rhyolitic melt; primarily SiO₂)
igneous
Obsidian
Volcanic Glass (comprised primarily of SiO2)
Igneous
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
igneous
Limonite (Iron Ore)
Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)
Mineral
Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
mineral